Part II of children are not just tiny adults: Newborn pain

I heard a great talk last week on neonatal pain. It was honestly not even a topic that I had considered before. Of course all humans have pain--it never even occurred to me that they might not. Apparently, it wasn't until about twenty years ago that the idea that a premature infant could even feel pain was medically accepted. The thought was that they were born before their pain circuits fully matured, and therefore were incapable of feeling pain. Newer studies in fact shown that premature infants are HYPER-sensitive to pain.

One great tip I learned while on my pediatric rotation is that the most important developmental milestone could be considered the social smile at 2 months old. Up until 2 months, it is very difficult to tell if a baby is in pain or sick. If a child has lost their social smile, there is an excellent chance they need more advanced medical care. So how do we tell if a newborn, or even more dramatically, a premature infant is in pain?

It is not as easy as you might think. Testing (and common sense) has shown that crying is completely non-specific. Babies cry if they are upset, hungry, tired, etc. Grimacing and withdrawal reflexes have also proven to be a poor indicators. Additionally, in the neonatal intensive care unit (NICU), for medical reasons, babies are often sedated or groggy from medications. This further blurs our ability to read any cues they might give us. There are >40 scales out there, but none of them are thought to be the ideal way to assess neonatal pain.

From the Archives of Pediatric and Adolescent Medicine is the study "Do we still hurt newborn babies?". In the NICU, in their study, each baby had on average 14 painful events each day. This ranged from pulling off tape, to heel sticks, to suctioning. Many times we don't even think to give any comfort during these procedures. Therapeutic options don't even have to be limited to just medication. You can dim the lights and noise to create less stressful environment and every medical student at some point has been on sweeties duty. This is where you dip the pacifier [or your finger] into a sucrose solution to let the baby calm itself on something sweet. This honestly works like magic. In this study, they found that less than 35% of newborns received any preceding intervention. Some studies suggest that neonates may be unable to experience the analgesic (pain relieving) effects of adult medications, such as morphine. They might just experience the sedative effects.

In my own work environment, cribs and incubators often have mirrors (so that the infants can look at themselves and receive visual stimulation), music, and mobiles. Hopefully other hospitals are also beginning to recognize the importance of treating neonatal pain; I just wish there were more quality studies out there to better guide us. Clearly, treating neonates like little adults just doesn't cut it.

Not only do neonates experience pain, they also remember it. The pain we experience as infants changes the way we will always react to pain. In mouse models, neonatal surgery affects the way adult mice react to pain stimuli. Similar results have been shown in humans. I have heard stories of former premature babies brought into the pediatrician's office who shriek if you touch their feet. Maybe they remember the heel sticks?